Reusable rocket engine nozzles are typically constructed from tubes brazed together inside a multi-piece high strength nozzle jacket and manifold assembly. The tubes carry a coolant to cool the rocket engine nozzle during operation. Another method of constructing rocket engine nozzles is by milling slots into a nozzle liner and bonding the nozzle liner into a nozzle jacket and manifold assembly. The slots of the nozzle liner and the interior surface of the nozzle jacket create channels for accommodating the coolant.
For tube nozzles, the tubes that accommodate the coolant receive coolant flow from a common inlet manifold and discharge the coolant into a common discharge manifold. To provide hot gas containment and coolant containment, braze joints are required at each tube-to-tube, tube-to-nozzle jacket and tube-to-manifold interface. This is typically accomplished with multi-braze cycles involving problems such as complex tooling to hold all of the parts in the proper relative position with adequate pressure at each braze joint, which typically requires expendable pressurized bags, interfaced to ensure a leak proof and structurally adequate braze joint.
U.S. Pat. No. 5,701,670, issued to Fisher et al. on Dec. 30, 1997, the entirety of which is hereby incorporated by reference herein, and that is assigned to the assignee of the present invention, discloses a method of fabricating a rocket engine combustion chamber having a structural jacket and a coolant liner. A throat support is assembled around the coolant liner. Then the coolant liner along with the throat support section is installed in the structural jacket. Once the coolant liner and throat support assembly is in place within the structural jacket, seal joints are made. Inlet and outlet manifolds are capped off for the bonding process. Internal voids created by coolant passages, inlet and outlet manifolds, and between the throat support and the structural jacket are evacuated by a vacuum pump. The entire assembly is then placed into a brazing furnace which is pressurized and brought up to bonding temperature.